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Carb adjustment

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Just bought a new needle for my son's xr 100 carb. Leaks out the overflow. There are three adjustments on the carb it seems: 1. the idle screw, 2. there is a screw with o-ring on the bottom of the float bowl and 3. screw with spring and o-ring on the base of the carb towards the cylinder. Can someone tell me what the starting point adjustment is for #2 and #3. Thanks

Noel

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The Service Manual only makes referene to the pilot screw initial setting: 2-5/8 before 1986, and 1-3/4 turns from 1986 and beyond.

andy t.

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Only two adj screws..........the one on the bottom of the float bowl is the float bowl drain!

Leaks out the overflow...............better check float level!:applause: Give us a year for your scooter and someone can give you the spec and describe how to check.

Old School Al

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Thanks guys! I'll set the pilot screw at 1 3/4 to start. The one on the bowl seems to be part of the vent tube and won't drain the bowl. Am I missing something obvious? It's a '98. I don't want to buy a manual as this is his last year on it, getting too big. Appreciate the help.

Noel

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My manual doesn't cover up that far in years, but what I have is 12.5mm (.49 in) for the float level. It could just be a stuck float, have you take the carb off to clean and inspect it?

andy t.

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Andy,

I have the carb off now. It looks like the needle is fine but I have a replacement. With the carb upside down with just float pressure against the spring the measurement is less than 12.5mm. I'll set that, clean the carb and see how it runs.

Noel

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Thanks guys! I'll set the pilot screw at 1 3/4 to start. The one on the bowl seems to be part of the vent tube and won't drain the bowl. Am I missing something obvious? It's a '98. I don't want to buy a manual as this is his last year on it, getting too big. Appreciate the help.

Noel

Either the vent tube or the drain is plugged, you'll have to check it out.

Andy's 12.5mm for float level is correct for 98. Measure from float bowl gasket surface to tip of float with needle seated, but not compressing spring in needle. Check both sides to make sure float isn't twisted (racked). :applause:

Old School Al

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Al,

Is just float pressure against the spring ok with the carb upside down? Thanks

Noel

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Weight of float upside down may try to compress spring you'll notice. I like to hold body with gasket surface vertical, float tip pointing down. Then lean body over 45 degrees or so to just seat needle, but not compress spring. Fiddle with it a bit and you'll see what I'm getting at.:applause:

Old School Al

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